Communications terminal

ABSTRACT

A communications terminal is provided which includes an antenna element, which has a specific antenna volume, and an acoustic output device, wherein the antenna element and the acoustic output device are designed and/or arranged with respect to each other such that at least part of the antenna volume forms at least part of a resonant cavity for the acoustic output device.

This application is a 371 of PCT/D E01/03615 Sep. 19, 2001.

BACKGROUND OF THE INVENTION

The present invention relates to a communications terminal having anantenna element, which has a specific antenna volume, and an acousticoutput device.

In the development of modern communications terminals, particularlymobile handheld devices such as mobile phones, palmtops or PDAs(Personal Digital Assistants) having appropriate mobile radio functions,minimizing the overall dimensions of the device is increasinglyimportant. At the same time, the device is meant to offer ever morefacilities with ever better quality, including optimizing thereproduction quality of the transmitted signals. Apart from improvingthe microphone of the transmitting communications terminal, this alsorequires the best possible transmission quality of the signal over theair interface, and a qualitatively good acoustic output device in thereceiving device.

Crucial for the transmission quality of the signals over the radionetwork are the antenna elements used by the device. In order to radiateand receive electromagnetic radiation in a specified frequency band,such an antenna element defines and requires a certain space, known asthe “antenna volume”, which must be kept as clear as possible ofobstructions to avoid effects on the antenna characteristics. Since theantenna elements in more modern devices are preferably integrated in thedevice, the communications terminal takes up a larger amount of space.In addition, the requirement for communications terminals with dual-bandcapability or multi-band capabilities means that the antennas need tooccupy even more space. Thus for given outer dimensions of the overalldevice, improvements in other components, which are again associatedwith an increased space requirement of the components concerned, aregenerally only possible by, for example, reducing the space for theantenna while accepting a degradation in the antenna properties.

An object of the present invention, therefore, is to create analternative mobile phone to the state of the art, which with minimumpossible dimensions provides a good antenna transmission quality whilealso providing a good acoustic output quality of the received signals.

SUMMARY OF THE INVENTION

According to the present invention, the antenna element and the acousticoutput device of the communications terminal are designed and/orarranged with respect to each other in such a way that at least part ofthe antenna volume forms at least part of a resonant cavity for theacoustic output device; for example, an earpiece. As a result of thepresent invention, the space available in the communications terminal isutilized very effectively in that the space required for the antennafunction is simultaneously optimized and designed as a resonant cavity.As such, the space inside the communications terminal is used for twodifferent functions without impairments to the one function arising fromthe use for the other function. For the antenna function, an air-filledinterior cavity area is optimum, because such an air-filled area onlyhas a small dielectric constant and does not cause any RF losses at all.The acoustics also need as large an air-filled area as possible asresonant cavity for optimum operation; for example, as a “back-cavity”volume at the back of an earpiece.

Preferably, the antenna element is disposed on an antenna supportcontaining a cavity having an opening on which the acoustic outputdevice is arranged in such a way that the cavity forms the resonantcavity for the acoustic output device. Obviously, the opening may alsotake the form of a number of small holes, a mesh or the like. The cavityshould be substantially soundproof, except for the opening or openingsplaced on the acoustic output device, so that the required soundpressure can be established at the opening(s) on the acoustic outputdevice.

Such a construction can be achieved, for example, by the antenna supportconsisting of a body made of non-conducting, (i.e., insulating),material containing a cavity having the relevant opening. This cavitythen forms the resonant cavity. Since the body is made of non-conductingmaterial, it can lie within the antenna volume. This means that, forexample, the antenna element can be applied outside on the body.Preferably, this takes the form of one or more conducting areas eachapplied to a surface of the antenna support.

In a particularly advantageous exemplary embodiment, the antenna supportalso contains a mounting for the acoustic output device. This can beimplemented, for example, by a recess made in the antenna support intowhich the earpiece is inserted and secured.

In a further preferred exemplary embodiment, the antenna support alsocontains one or more integral screened cavities for screening specificareas within the communications terminal; for example, areas on acircuit board that are susceptible to EMC from the RF radiation emittedfrom the antenna. These screened cavities can be formed by recesses madein the surface of the body forming the antenna support and coatedinternally with a conducting layer, where the antenna support must bepositioned at the appropriate position on the circuit board so that therecess covers the area to be screened on the circuit board.

For maximum efficiency when fitting such an antenna support having theantenna element and the acoustic output device, the antenna supportpreferably also contains contact elements for making conductive contactwith the antenna element and/or the acoustic output device and/or thescreened cavity. The antenna support having the applied antennaelements, the pre-fitted acoustic output device (or, specifically,earpiece), and the finished screened cavity with the associated contactelements, can simply be placed as a prefabricated module at the requiredposition on the circuit board during final assembly of thecommunications terminal. By designing the contact elements to thecircuit board to be elastic so as to create pressure contacts, otheradditional work operations such as contact soldering can be avoided.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a perspective view of an antenna module that basicallyincludes an antenna support with an applied antenna element for fittingin a communications terminal according to the present invention.

FIG. 2 shows a central longitudinal section through the antenna moduleof FIG. 1.

FIG. 3 shows a cross-section through the antenna support of the antennamodule in FIG. 2 along the intersection line A–A′.

FIG. 4 shows a plan view from above the antenna module of FIG. 1.

FIG. 5 shows a plan view from below the antenna module of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The figures show an antenna module for a communications terminalaccording to the present invention; specifically, a mobile phone. Thismodule has an antenna support 4 which is basically formed as anon-conducting plastic body 11. This antenna support 4 is coated on twoopposite surfaces with specially patterned conducting areas 1 a, 1 bforming a two-piece antenna element 1. The antenna volume extendsbetween the conducting areas 1 a, 1 b. This antenna module is placed insuitable contact with a printed circuit board 20 of the mobile phone atthe intended position in the mobile phone.

The design and shape of the antenna module are described in detailbelow.

The plastic body 11 forming the antenna support 4 consists of two joinedhalf-shells, which thereby create a cavity 5 inside the plastic body 11.For good sound quality, the resonant cavity 3 should have a maximumvolume. The cavity 5 is therefore chosen to be as large as possible,while taking care that the remaining wall thickness of the plastic body11 guarantees sufficient rigidity. With regard to the outer shape, theplastic body 11 is designed to fit the case shape, or rather the spaceavailable in the mobile phone, and the required three-dimensional shapeof the antenna element 1 or the antenna volume 2.

Accordingly, the plastic body 11 has a substantially flat side, which isalso referred to below as the front face. There is a recess 7 in thefront face, into which an earpiece (not shown) is inserted at assembly.There are a number of holes 6 between the recess 7 for the earpiece andthe cavity 5, so that the cavity 5 forms a resonant cavity 3, moreprecisely a back-cavity volume, for the suitably designed earpieceintroduced into the recess 7.

Beside the recess 7 on the front face of the plastic body 11, there isanother recess which forms a screened cavity 8 integrated in the antennasupport 4. Components of the mobile phone that are susceptible to RFinterference and requiring particular protection, such as a displaycontroller, can be housed inside this screened cavity 8. Components thatneed to be screened owing to their tendency to create interference, forinstance an output stage of the transmit device which emits unwantedharmonics, also can be housed in the screened cavity.

On the rear face opposite the front face, the body 11 is shaped to fitthe shape of the mobile phone case. In the present exemplary embodimentthis is a module for a mobile phone having a case with a rounded backand top. The rear face, consequently, also is shaped with a matchingconvex curve.

The antenna element 1 itself consists of two conducting areas applied tothe front face and back face 1 a, 1 b. These surfaces have the patternrequired for the antenna function. The precise shape, or rather pattern,of the antenna is here arbitrary for the present invention and dependson the frequency bands in which the antenna is meant to work. In thepresent exemplary embodiment, the antenna is a “PIF” (Planar Inverted F)antenna. On the front face of the body 11, the conducting area 1 b ofthe antenna element also runs continuously on the interior sides 10 ofthe recesses 7, 9 for the earpiece and screened cavity 8. As such, thethis conducting area 1 b acts as part of the antenna element 1, whilealso forming the screening for the earpiece and the screened cavity 8.

The whole module is then placed, as shown in FIG. 2, with part of thefront face on the circuit board 20 of the mobile phone, so that thescreened cavity 8 is located directly over the circuit board 20, and therecess 7 for the earpiece lies beyond the top end of the circuit board20 within the case of the mobile phone. On the circuit board 20 arecontact surfaces, which make contact with the front-face conducting area1 b of the antenna element 1 when the module is placed on the circuitboard 20. This front-face conducting area 1 b of the antenna element 1is thus taken to the ground potential of the mobile phone.

Preferably, elastic contacts are disposed on the conducting area 1 bthat ensure reliable pressure contact with the contact surfaces on thecircuit board 20. The exemplary embodiment shown has multiple contactpoints along the periphery of the screened cavity 8 which are positionedrelatively closely to each other so as to ensure that the cavity 8 isscreened against RF interference. Metal springs, for example, or evendrops of conductive silicon applied as spot-shaped contacts, may be usedto form the elastic contact points. Of course, instead of thespot-shaped contacts along the periphery of the screened cavity, acontinuous string of conductive silicon or the like also can be applied.

In the exemplary embodiment shown, the pattern of the conducting area 1b on the front face of the module is chosen so that conducting patterns15 having appropriate contact points 17, 18 are also integrated in themodule for making contact with the earpiece. These patterns 15 also maybe elastic metal springs or printed patterns provided with, for example,an elastic conductive silicon or the like at each of the contact points17, 18.

During operation, the RF signal is applied to the conducting area 1 a ofthe antenna element 1 applied to the rear face of the plastic body 11.This is done via at least one, preferably multiple contact strips 13, 14(three in the present case), which stretch from the rear face of theplastic body 11 around one edge to the front face of the plastic body11, and are there provided with elastic contact points 12, 16, which inthe assembled state press onto corresponding contact elements on thecircuit board 20.

In the plastic body 11, there is also a through hole 21 passing from therear face to the front face to accommodate a coaxial connector forconnecting an external antenna. This hole 21 runs beside the cavity 5and the screened cavity 8, i.e., it has no effect on the resonant cavity3 nor the screened cavity 8. The antenna support 4 thus additionallyprovides a rigid support for the coaxial connector of an externalantenna; for example, the antenna of a vehicle hands-free device. Theinner conductor 19 of this coaxial connector is connected via a contactstrip 13 and corresponding contact point 16 to the conducting area 1 aon the rear face of the plastic body 11 and to the circuit board 20, sothat the RF signal is also present here. The outer conductor (i.e., theRF connector screening), is correspondingly connected to the groundpotential (i.e., the conducting area 1 b on the front face of theplastic body 11).

The introduction of the patterns 13, 14, 15 for the contacts, the hole21 for the coaxial connector and the openings 6 into the conducting area1 a, 1 b normally does not impair the antenna function, since thesepatterns 13, 14, 15, hole 21 and openings 6 are either relatively smallin relation to the overall surface area, or can be taken into accountwhen designing the antenna structure.

The present invention provides optimum utilization of the spaceavailable in the mobile phone. The necessary antenna volume 2 isadvantageously used for improving the acoustics. In addition, theantenna support provides a screening function for specific areas on acircuit board 20 of the mobile phone, plus a retaining function for anearpiece or a loudspeaker. Hence, a separate mounting for the earpieceis not required, wherein the cost may be reduced. Furthermore, itensures that contact is made reliably and simply with the antenna, thescreening and the earpiece. Using the rigid plastic body 11 for theantenna support 4, onto which the antenna element 1 is applied asconducting areas 1 a, 1 b, also avoids tolerance problems that arise inan antenna construction without extra support. The whole finished moduleis thus relatively easy and economic to manufacture, and can be fittedquickly and without great effort during assembly of the mobile phone.

Although the present invention has been described with reference tospecific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the present invention as set forth in the hereafter appended claims.

1. A communications terminal, comprising: an antenna element having an antenna volume; an antenna support comprising contact elements, a cavity with an opening, and a mounting, wherein the antenna element is arranged on the antenna support; and an acoustic output device arranged on said mounting, wherein the antenna elements and the acoustic output device are particularly arranged such that at least part of the antenna volume forms at least part of a resonant cavity for the acoustic output device, and wherein the acoustic output device is operatively coupled to the contact elements.
 2. A communications terminal as claimed in claim 1, wherein the acoustic output device is particularly arranged such that the cavity forms the resonant cavity for the acoustic output device.
 3. A communications terminal as claimed in claim 2, wherein the antenna support includes a body made of non-conducting material having at least one of a recess and at least one cavity.
 4. A communications terminal as claimed in claim 2, wherein the antenna support includes two half-shells.
 5. A communications terminal as claimed in claim 2, wherein the antenna element further includes at least one conducting area applied to a surface of the antenna support.
 6. A communications terminal as claimed in claim 2, wherein the antenna support includes a recess on an outer side in front of the opening of the cavity for receiving an ear piece.
 7. A communications terminal as claimed in claim 1, wherein the antenna support includes a screened cavity.
 8. A communications terminal as claimed in claim 7, wherein the contact elements are further operatively coupled to at least one of the antenna element and the screened cavity.
 9. A communications terminal as claimed in claim 7, wherein the screened cavity is formed by a recess in the antenna support coded internally with a conducting layer.
 10. A communications terminal as claimed in claim 1, wherein the communications terminal is a mobile phone. 